JPH0448079Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a piezoelectric speaker having drip-proof and waterproof properties.

(Prior Art) Conventionally, as shown in FIG. 2, for example, as shown in FIG. It is well known that the periphery of the diaphragm 5 of the sounding body 4 is adhered to the elastic support 2 using an adhesive 3. The sounding body 4 has a piezoelectric element 6 attached to one main surface of a diaphragm 5, and an electrode 6a formed on the piezoelectric element 6 and the diaphragm 5.
Lead wires 7 and 8 are soldered to the ends, respectively. When electrical signals are applied to these lead wires 7 and 8, the piezoelectric element 6 bends and vibrates, driving the diaphragm 5 and generating sound.

By the way, in the piezoelectric speaker having the above configuration, it is difficult to perfect the adhesion between the elastic support 2 and the frame 1 and the adhesion between the elastic support 2 and the diaphragm 5 of the sounding body 4. Ta. Therefore, the frame 1 is passed through the hole 1a of the frame 1 through the adhesive part between the elastic support 2 and the frame 1 and the adhesive part between the elastic support 2 and the diaphragm 5 of the sounding body 4.
There is a problem in that water enters the inside of the frame 1 from the outside, and the piezoelectric speaker shown in FIG. 2 has a problem in that it is inferior in waterproof and drip-proof properties. Also, the second
In the piezoelectric speaker shown in the figure, a sounding body 4 is placed inside the frame 1.
Since the piezoelectric element was exposed, there was a problem that the environmental resistance was low.

In addition to the above-mentioned drip-proof and waterproof piezoelectric speakers, although not specifically shown, a sounding body similar to the piezoelectric speaker shown in Fig. 2 is directly adhered to a resin film, and then It is also well known that two resin films are covered with another resin film and bonded to each other at their peripheral edges.

In devices with such a configuration, the sounding body of the piezoelectric speaker is bonded to a thin and flexible resin film, so the damping characteristics of the sounding body are poor, and the sounding body of the piezoelectric speaker has poor damping characteristics, such as high o (o is the resonant frequency) and high becomes Q,
There was a problem that the frequency characteristics had large peaks and valleys and poor flatness.

(Purpose of the invention) An object of the invention is to provide a drip-proof and waterproof piezoelectric speaker that achieves wide-band and flat frequency characteristics.

(Structure of the Invention) Therefore, in the present invention, the diaphragm of the sounding body to which the piezoelectric element is bonded has a ring-shaped first ring on the periphery of the main surface on one side and on the periphery of the main surface on the other side.
One surface of each of the elastic support and the second elastic support is bonded, and another surface of each of the first and second elastic supports is bonded to each of the first and second formed films. The first molded film and the second molded film are each bonded to the bottom surface of the recess facing the opening of the recess, and are bonded to each other at their peripheral edges.
The sounding body is sealed between a first molded film and a second molded film, and is elastically supported by a first elastic support and a second elastic support.

(Effect of the invention) According to the invention, since the first molded film and the second molded film are heat-welded at their peripheral edges, the sounding body is placed between the first molded film and the second molded film. A sealed piezoelectric speaker with good drip-proof and waterproof properties can be obtained. Further, according to the present invention, since the sounding body is elastically supported by the first and second elastic supports within the recesses of the first and second molded films, the sounding body is symmetrically supported from both principal surfaces of the sounding body. Braking is applied by the first and second elastic supports, so that the sounding body has a low o and a low Q, and a piezoelectric speaker having flat frequency characteristics can be obtained. Furthermore, according to the present invention, since the sounding body is not directly in contact with or bonded to the first and second molded films, the acoustic impedance is reduced and the matching with the air is improved, making it possible to create a highly efficient piezoelectric speaker. Obtainable.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a longitudinal section of an embodiment of a piezoelectric speaker according to the present invention.

The piezoelectric speaker has a total thickness of about 1.8 mm and includes a sounding body 11 and a first ring-shaped speaker.
The elastic support 12 and the second elastic support 13, and the first elastic support 12 and the second elastic support 1
The first molded film 14 made of resin is integrally formed with recesses 14a and 15a for accommodating 3, respectively.
and a second molded film 15.

The sounding body 11 has the same structure as the sounding body 4 of the piezoelectric speaker explained in FIG. A piezoelectric element 17 is attached to the piezoelectric element 17. This piezoelectric element 17 has an electrode 17a formed on a surface opposite to the diaphragm 16.

The first elastic support 12 and the second elastic support 13, which elastically support the sounding body 11, each have a thickness of about 0.8 mm and are formed from a material such as foamed polyurethane or foamed polyethylene into a ring shape. It is. The first elastic support 12 has adhesive layers 12a and 12b formed on both surfaces thereof, respectively. Further, the second elastic support 13 also has adhesive layers 13a and 13b formed on both surfaces thereof, respectively.

The first elastic support 12 is attached to the periphery of one main surface of the diaphragm 16 of the sounding body 11 with an adhesive layer 12a formed on one surface thereof.
and are glued concentrically. Similarly, the second elastic support 13 has an adhesive layer 1 formed on one surface thereof.
At 3a, it is adhered to the peripheral edge of the other main surface of the diaphragm 16 of the sounding body 11, concentrically with the diaphragm 16.

On the other hand, the first molded film 14 and the second molded film 15 are both made of resin films such as polyester, polycarbonate, or polyimide, each having a thickness of about 0.1 mm. First molded film 14
The concave portion 14a is formed by extruding a region of the resin film from the center to the vicinity of the periphery from one side to the other. The concave portion 15a of the second molded film 15 is also formed in the same manner.

The first bonded to the diaphragm 16 of the sounding body 11
The elastic support 12 and the second elastic support 13 are accommodated in the recesses 14a and 15a of the first molded film 14 and second molded film 15, respectively. The first elastic support 12 is adhered to the bottom surface of the recess 14a of the first molded film 14 by the adhesive layer 12b on the other side, and the second elastic support 13 is attached to the bottom surface of the recess 14a on the other side by the adhesive layer 13b on the other side. It is adhered to the bottom surface of the recess 15a of the molded film 15.
The first molded film 14 and the second molded film 15 are thermally welded to each other at their peripheral edges.

Note that during this heat welding, the lead wire 18 soldered to the electrode 17a of the piezoelectric element 17 of the sounding body 11
The lead wires 19 soldered to the diaphragm 16 of the sounding body 11 are both drawn out from between the heat-welded surfaces of the first molded film 14 and the second molded film 15.

With such a configuration, the sounding body 11
Since the molded film 14 and the second molded film 15 are heat-welded to each other at their peripheral edges, the sounding body 1
1 is sealed between the first molded film 14 and the second molded film 15 within the recess 14a of the first molded film 14 and the recess 15a of the second molded film 15. Therefore, the piezoelectric speaker in Fig. 1 is
Even if water is immersed in water or water droplets are formed, water will not enter into the recesses 14a and 15a.

Further, since the sounding body 11 is damped by the first and second elastic supports symmetrically from both sides of the diaphragm 16 at the peripheral edges of both main surfaces of the sounding body 11, the sounding body 11 is Low o results in low Q. As a result, the frequency characteristics of the piezoelectric speaker shown in FIG. 1 become flat.

Furthermore, since the sounding body 11 is supported without contacting the first molded film 14 and the second molded film 15, the acoustic impedance is reduced, the matching with the air is improved, and the efficiency of the piezoelectric speaker is improved.

Note that the piezoelectric speaker shown in FIG. 1 has a symmetrical outer shape with respect to the diaphragm 16 of the sounding body 11, so there is no directionality in its mounting.

Further, since the first molded film 14 and the second molded film 15 have recesses 14a and 15a, respectively, when the first molded film 14 and the second molded film 15 are thermally welded to each other at their peripheral edges, , the occurrence of wrinkles and deformation in this peripheral portion is suppressed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of a piezoelectric speaker according to the present invention, and FIG. 2 is a longitudinal sectional view of a conventional piezoelectric speaker. 11...Sounding body, 12...First elastic support, 1
3...Second elastic support, 12a, 12b, 13
a, 13b...adhesive layer, 14...first molded film, 15...second molded film, 14a, 15
a... recess, 16... diaphragm, 17... piezoelectric element.

Claims (1)

[Claims for Utility Model Registration] A sounding body in which a piezoelectric element for driving the diaphragm is bonded to a diaphragm; a ring-shaped first elastic support body bonded together; a ring-shaped second elastic support body one surface of which is bonded to the peripheral edge of the other main surface of the diaphragm; a first molded film having a concave portion for accommodating the first elastic support formed by extruding a region near the peripheral edge of the resin film from one side to the other; and a center of another resin film. and a second molded resin film having a concave portion for accommodating the second elastic support formed by extruding a region extending from one side of the resin film to the vicinity of the peripheral edge thereof, from one side of the resin film to the other side, Another surface of each of the first elastic support and the second elastic support is connected to the first formed film and the second elastic support.
A piezoelectric speaker characterized in that the first molded film and the second molded film are bonded to each other at their peripheral edges, and each of the first molded film and the second molded film is bonded to the bottom surface of each recess facing the opening of each recess of the molded film.